Electric time-switch.



J. H. ROBERTSON.

ELECTRIC TIME SWITCH.

APPLICATION FILED mums, 1912.

1, 1 27,375. Patented Feb. 2, 1915.

3 SHEETSSHEET 1.

NR) QN J. H. ROBERTSON.

ELECTRIC TIME SWITCH.

APPLICATION FILED MAR.16, 19124 Patented Feb. 2, 1915.

3 SHEETS-SHEET 2.

J. H. ROBERTSON.

ELECTRIC TIME SWITCH.

APPLICATION FILED MAR.16, 1912.

1,127,375, 4 Patented Feb. 2, 1915.

3 SHEETS-SHEET 3 HE NORRIS PE7ERS CO., PHOTO'LITHO WASHINGTON, D c.

UNITED OFFICE.

JOHN H. ROBERTSON, OF PLATTEVILLE, WISCONSIN.

ELECTRIC TIME-SWITCH.

Application filed March 16, 1912.

To all whom it may concern Be it known that I, Jorm H. ROBERTSON, a citizen of the United States of America, and a resident of Platteville. county of Grant, State of lVisconsin, have invented certain new and useful Improvements in Electric T ime-switches, of which the following is a specification.

The main objects of this invention are to provide improved means for controlling the operation of motor actuated mechanism, so that it may be set for operation so as to automatically perform a certain operation at the expiration of a predetermined interval of time. and particularly to provide an arrangement 01 clock mechanism suitable for the operation of time switches and adapted through the manual closing of the switch to be set to cause the opening of the switch at the end of a predetermined interval of time; to provide a time switch mechanism of this kind which will permit the switch to be opened manually at any time regardless of whether or not the timing is set; to provide an improved construction for spring actuated time switches whereby a force in the nature of a hammer blow will be suddenly applied to the switch mechanism to start the opening thereof. and thereby assist the motor mechanism; to provide a construction of this kind which is particularly adapted for use in connection with knife or snapswitches; to provide improved means for indicating the time interval for which the switch has been set and how much of this interval is unexpired; and to provide certain improvements in devices of the type covcred in my prior Patent No. 659,766 of Ootober 16, 1900. In prior devices of this kind, as exemplified by my said patent, a springmotor driven timing device has been set by means of the winding key of the motor so as to run down in a certain interval of time and automatically release a switch at the expiration of such interval of time. In order to apply such mechanism to knife-switches and snap-switches. controlling electric lighting and other high tension circuits, it is essential that the switch be opened suddenly and be quickly thrown from a full closed position to a full open position. It has been usual to rely upon the strength remaining in the spring of the spring-motor in conjunction with that of an auxiliary spring normally tending to open the switch after it has been released through the running down of Specification of Letters Patent.

Patented Feb. 2, 1915.

Serial No. 684.300.

the spring-motor. Such devices require an extremely powerful auxiliary spring on account of the friction of the switch clips and other parts. and I have found that much better results can be obtained if the power of the auxiliary spring is so controlled as to be suddenly released to impart a hammer blow to the movable switch member at the instant that it is released by the timing device.

A. further object, therefore, of this invention is to provide an improved hammer mechanism for this purpose and to provide an improved arrangement of a plurality of springs whereby their power may be most effectively applied to the switch.

A specific embodiment of this invention is illustrated in the accompanying drawings in which:

Figure 1 is a front ele ation of a time switch constructed according to this invention, the front cover, dials and winding key being omitted to more clearly disclose the mechanism beneath. Fig. 2 is a longitudinal section of the same taken on the line AA of Fig. 1. Figs. 3, 4, 5, and 6 are details illustrating different positions of the parts of the switch actuating mechanism. Fig. 7 is a detail of the trip mechanism forming a part of the mechanism shown in Figs. 3 to 6 and illustrating the position of the parts during a return movement of the switch actuating mechanism. Fig. 8 is a detail of the dial of the timing device. Fig. 9 is an enlarged fragmentary detail showing the arrangement of lugs between the dials. Fig. 10 is a further detail of the same. Fig. 11 is a sectional detail taken on the line 13-13 of Fig. 8. Fig. 12 is a detail of the switch dial. Fig. 13 is a sectional detail taken on the line CC of Fig. 14. Fig. 14 is an en larged detail of the dog or detent which looks the switch actuating bars together. Fig. 15 is a sectional detail of the key for winding the spring of the motor and setting the switch mechanism. Fig. 16 is a detail showing the manner of mounting the roller stop which holds the switch operating mechanism in its set position.

In the construction shown in the drawings the switch 1 and the timing device 2 are mounted in a single casing 3. The switch may be of any ordinary type, and, in the form shown, it is a four-pole switch comprising four movable blades 1 mounted upon an arbor 5, and coacting with a corresponding set of pairs of spring contact clips 6 which may be connected to conductors '7 in such manner as to suit any specific conditions.

The member 8 which carries the switch blades 4 is connected by means of a stud 9 with a dial disk 10 pivotally mounted in axial alinement therewith on the front wall 11 of easing (see Fig. 2), and this wall is 1 provided with a window or sight opening 12 through which the characters on the disk 10 may be read. These characters, as indicated in Fig. 12, may be the words On and Off or other symbols to indicate the position of the movable switch parts. In the form shown the switch blades simply have two positions and oscillate back and forth between these positions. Movement of the member 8 is brought about by an oscillating member 13 which is also pivotally mounted on the central stud 5 and which has a pair of spaced shoulders 14 and 15 located to engage a pin or shoulder 16 on the blade member 8. A light spring 17 extends between the pin 16 and a stud 18 on the member 13 and normally urges the two members to the relative positions shown in Fig. 1, with the pin 16 abutting against the shoulder 15. A compression spring 19 acts between a pivoted stud or shoulder 20 on the frame, and a stud or shoulder 21 on the member 13 so as to urge said member toward either of the limits of its oscillatory movement after it has passed the middle point of such movement. This spring will be herein called a toggle-spring because of its resemblance to one of the links of a toggle-joint made up of said spring and the arm of the member 13. The expression toggle-spring is used for lack of a better expression to designate the general class of springs of this character which, as is well-known, may be either compression or tension springs. The spring 19 is held in place by means of a rod 22 running through and having sliding connection with an aperture in the stud 21. A second stud 23 on the member 13 engages a slot 24 in a pair of operating bars 25 and 26 which he one above the other in Fig. 1, and are moved longitudinally, by mechanism hereinafter described, for opening and closing the switch.

The timing device and operating mechanism, designated as a whole in the drawings by the reference numeral 2, comprises mechanism for operating the switch both manually by a key 27 and automatically by a clock-work not shown in detail but represented in the drawings by the gear casing 28, the fly 28 and the motor spring 29. The operation of the switch mechanism during the winding and unwinding of the motor spring is controlled bya Geneva stop mechanism comprising a star wheel 30 and a one toothed gear 31. In the present construction, as in my prior patent above mentioned, the one-toothed gear 31 is not rigidly con nected with the winding shaft 32 of the motor spring but is mounted directly on the stem 33 which has telescoping threaded conhection with the shaft This threaded connection has a right-handed thread so that when the winding key 27 is turned in a clockwise direction the motor spring will be wound up. The operating mechanism is also arranged, as will hereinafter appear, so that this right-handed turning of the key 27 will close the switch. By reason of the threaded connection the winding key may be turned back counter-clockwise to open the switch at will independent of the clock work, for opening the switch. The star Wheel 30 is made of sufficient thickness to remain in mesh with the gear 31 when the stem 33 is turned on its threaded connection with the shaft 32. The method of mounting the key 27 on the stem 33 will be readily understood from Fig. 15.

The switch operating mechanism comprises, in addition to the key 27 and th Geneva stop gearing, a mutilated gear 34, having fixed relation to the star wheel 30 so as to be rotated therewith, and a rack comprising a series of teeth on the bar 26. The bar 26 has an arm 36 adjacent to the gear 34, and this arm is provided with a notch 37 which has shoulders at its sides located to coact with a lug or tooth 38 on the mutilated gear 34. In order to assist the motor spring of the clock-work in pulling the bars 25 and 26 against the action of the spring 19, and to also assist the spring 19 in opening the switch after said spring 19 has passed its dead point, there is provided a strong tension spring 39 which is connected at one end to the casing and at the other end to a stud 40 on the bar 25. The bars 25 and 26 are held in their set positions, as illustrated in Fig. 1, by means of a roller stop 41 extending between the gear casing 28 and a guide bracket 42. Shoulders at the upper ends of the bars 25 and 26 engage this roller stop when said bars are in the position shown in Fig. 1. The switch opening spring 39 is slightly inclined to the bar 25 when the latter is swung inwardly to release it from the stop 41. Hence the spring 39 has a biasing effect on the bar 25, tending to swing its upper end toward the left in Fig. 1. To further control the relative movements of the bars 25 and 26, a pin 43 on the bar 26 coacts with the edges of a cam shaped slot 44 in the bar 25, and the bar 25 also has pivotally mounted thereon a dog 45, shown in detail in Figs. 13 and 14, and shaped to engage notches 46 and 47 in the edge of the bar 26. The dog has a tail 48 coacting with a spring 49 for normally urging the dog into position with the dog 45, has a shoulder 51 located to engage the dog for retracting it against the action of the spring 49. The finger 50 is normally urged by a light spring 52, weaker than the spring 49, to the position in which it is shown in Fig. 14. This finger coacts with a stationary shoulder 53, on the frame for tripping the (log 45, as the bars move in the direction which is upward in the drawings. The various positions of the dog and its associated parts during the upward movement of the bars is illustrated in Figs. 3 to 6 inclusive, and the manner in which the finger 50 may yield to pass the shoulder 53 during the downward movement of the bar 25 is shown in Fig. 7.

In order to provide suitable means for indicating the period of time for which the switch has been set, and also for indicating how much of that period remains at any time before the switch opens automatically, an indicating device is provided which has two indicators. These in the form shown are the dials 54 and 55 journaled on a common axis one above the other, and each provided with an annular series of figures positioned to appear at the window or sight opening 56 in the front of the casing. The larger dial 54 has gear teeth on its periphery meshing with a pinion 57 on the key stem This pinion, or the dial itself, should be wide enough to permit them to remain in mesh during the axial movementof the stem 33 when rotated on its threaded connection to the shaft hereinbefore described. Thus the dial 54 indicates the extent to which the key 27 has been turned in setting the switch. and since it turns back as the clockwork runs, it also indicates how much of the time interval remains at any time. The smaller dial 55 is mounted on the same stud 58 that carries the dial 54, and the two dials are provided with shoulders 59 and 60 which abut against each other in such manner that when the dial 54 is set to any indication the dia] 55 will be carried to a like indication. The dial 54 may, however, turn back without carrying the dial 55 along. The dial 55 is normally urged back to its zero position by a spring 61 acting between it and a stationary stud 62. The edge of the dial 55 is provided with ratchet teeth coacting with a pawl 63 mounted on a stationary pivot and provided with a tail 64 located to engage a pin 65 on the dial 54, the pin being so located that it will trip the pawl 63 when the dial 54 reaches its zero position. thus releasing the dial 55 and allowing the spring 61 to return it to its zero position.

In order to prevent any possibility that the key 27. by means of which the device is set. shall be alive it is insulated in the following manner. The rectangular stem 33 is surrounded by a tube of insulating material 27", which in turn is surrounded by a metal tube 27 serving as a reinforcement for the tube 27 Embedded within the body of the head of the key 27 is a nut 27". The key 27 is, therefore. of composite construction, the parts 27, 27, and 27 being all removable as a unit from the stem 33. The key 27 is secured against loss from the stem 33 by means of a screw 27 which has its head countersunk in the key 27 and has a threaded shank fitting the nut 27 and extending through a hole in the upper end of the stem 33, which hole is suitably lined with insulation 27 If the screw is removed the key, including the metal tube and insulating tube, can be readily removed from the stem 33 leaving the bushing of insulation 27 in the hole in the stem.

In practical use, if in case of accident the insulating head be broken ofl, the metal tube 27 will protect the insulating tube 27, and it will. therefore, be impossible for a live part to become accidentally exposed through the casing. The shaft 32 being weaker than the stem 33. would break ofl inside the cover before any of the other parts would break.

The operation of the device shown is as follows: The initial or open position of the switch operating mechanism is that in which the parts are shown in Fig. 6. Fig. 1 shows the position of the parts after the mechanism has been set by the operator on closing the switch. Assume now that the parts are in the position corresponding to Fig. 6, that is to say the switch is open. the spring 19 is expanded in its right-hand position. the bars 25 and 26 are elevated, the detent 45 is in the upper notch 46 of the bar 26, and the rack 35 is in mesh with the teeth A of the gear 34 as in Fig. 6. To set the switch the operator turns the key 27 in a clockwise direction, this winds the main spring 29 and sets the dials of Fig. 8 to indicate the interval of time for which the switch meehai nism has been set by indicating the angular extent to which the key is turned. For instance. if the operator wishes to set the switch for ten minutes he turns the key 27 until the number 10 appears at the sight 5 opening 56. The gearing turns the outer dial 54, and the pins 59 and 60 cause the inner dial to turn with it. The pawl 63 now holds the inner dial in this position. but

the outer dial may turn back as the clock- 7? work runs. As the operator turns the key 27 the gear 31 rotates the star wheel 30 and simultaneously rotates the gear 34 in the direction of the arrow 66 on Fig. 6. This causes the rack 35 to be moved downward,

holding the rack 45 in mesh with the gear 34. As soon as the rotation of the gear 34 has carried the bars 25 and 26 to the lower limit of their movement the single tooth 38 will have gone into mesh with the recess 37 on the arm 36 of the bar 26. Continued rotation of the gear 34 in a counter clockwise direction causes the tooth 38 to engage the shoulder at the left hand side of the recess 37 on the bar 26, and thereby forces said bar toward the left of Fig. 1 so that its end shoulder will abut against the roller stop 41. The pin 43 causes the bar 25 to move with the bar 26 and be set behind the roller stop. This same movement of the tooth 38 throws the rack out of mesh with the teeth of the gear and permits the further 11 tation of the gear 34 without affecting the rack. It may thus be set to return in any predetermined period of time Within the limits for which the device has been designed, as determined by the gear ratio between the winding key and the gear 34. The spring 39 now holds the bars 25 and 26 against the roller stop 41, and as the spring is slightly inclined to the bars in a direction toward the left of Fig. 1 it tends to resist the unseating of the shoulders 68 and 69 from the roller stop 41. During the downward movement of the bars 25 and 26, under the power exerted by the operator in setting the device, the shoulder formed by the up per end of the slot 24 engages the stud 23 and shifts the member 13 against the action of the toggle spring 19 until said spring has passed the dead point, whereupon said spring causes a rapid continuation of the counter clockwise movement of the member 13 causing the shoulder 15, through its contact with the stud 16, to force the blade member 8 of the switch quickly to a closed position. This shifting of the blade member and the setting of the bars 25 and 26 behind the stop 41., is accomplished by a comparatively small movement of the winding key. If the operator desires to open the switch before the clockwork has automatically opened it, he merely needs to turn the key backward, that is counter clockwise, until the dial returns to zero. This, on account of the threaded connection between the stem 33 and shaft 32, may be done without a ffecting the clock mechanism, and the operation of the gearing under this condition is the same as that which is brought about by the clockwork and which will be hereinafter described. \Vhen the device has been set as above described the upper dial will indicate the time interval for which the clockwork has been set, and the lower dial will indicate On to show at a glance that the switch is closed. After the device has been set the parts will be in the position indicated in Fig. 1, although the single tooth 38 may be shifted a considerable angular extent to the left from the position in which it is there shown. The position in which it is shown is the position which it occupies at the instant when the clockwork commences the operation of opening the switch. hen the tooth 38 arrives at the position in which it is shown in Fig. 1, under the power of the spring 29 which rotates the gear 34 in a clockwise direction, it engages the righthand side of the notch 37 and pulls the bar 26 toward the right until it has brought the rack into mesh with the teeth of the gear 34 and pulled the shoulder 68 clear of the roller stop 41. The same movement moves the pin 43 clear of the end of the guide 42 and continued rotation of the gear 34, in direction of the arrow of Fig. 3, advances the bar 26 and forces the pin 4.3 into the space between the right-hand end of the guide 42 and the inclined shoulder 71 of the slot 44 in the bar 25. This causes the pin 43 to shift the bar 25 toward the right until the shoulder 69 has been moved clear of the roller stop 41, whereupon the spring 39 is permitted to assist the clockwork in pulling the bars 25 and 26 and in overcoming the pressure of the spring 19. Just before this shoulder 69 is cleared from the roller stop 41 the bar 26 has advanced in an upward direction, in relation to the bar 25, a disstance equal to the distance between the notches 46 and 47 in the bar 26 and the detent 45 has dropped into the notch 47, the bars and 26 being held in this relationship to each other as they advance upward together, the lower end of the slot 24 in the bar 25 being thus held at a distance below the pin 23, (see Figs. 3 and 4) for reasons to be explained. In Fig. 4 the parts are illustrated in the position which they occupy immediately after the spring 19 has been shifted past its dead point. At this instant the finger 50 comes into contact with the shoulder 53 and trips the dog 45 so as to release the bar 25 from the rack bar 26 and allows the bar 25 to be suddenly shot u ward under the action of the spring 39 to t e position in which it is shown in Flg. 5.

Reverting to Figs. 3 and 4 it will be noticed that in the positions there shown the pin 23 is at the lower end of the slot 24 in the bar 26, but it is a considerable distance above the lower end of the slot 24 in the bar Therefore, when the sudden upward movement of the bar 25 takes place it travels a considerable distance under the pull of the spring 39 and acquires momentum so that when the lower end of the slot 24 strikes the pin 23 it will have an impact similar to a hammer blow. This starts the movement of the switch member 8 with a jerk and then the combined action of the springs 39 and 19 rapidly swings the switch member 8 so that its blades will suddenly break contact with the members 6 and thereby prevent much of the arcing which occurs when an electric switch in a high tension circuit is slowly opened. It is to be also noted that in Fig. 4 the spring 17 is stretched. This serves to throw the switch member 8 to a certain extent beyond the point to which it is thrown by the spring 19. When the parts have arrived in the position in which they are shown in Fig. 5, the dog will have passed the uppermost notch 46 and will bear against the side of the bar 26 ready to fall into said notch 46 when the same arrives at the position for registering therewith, which position is indicated in Fig. 6 and is reached when the gear 34 has been rotated in a clockwise direction to approximately the limit of its movement. This is the normal initial position of the parts, corresponding to the open switch, and is the position in which the Geneva stop gearing stops the clockwork.

When the operator wishes to reset the mechanism he turns the key in a clockwise direction and causes the gearing to shift the bars and 26 toward the bottom of Fig.

6, as hereinbefore described, during such movement the finger 50 trails over the shoulder 53 in the manner in which it is shown in Fig. 7.

303 The operation of the dial 10 is obvious from the drawings.

Although but one specific embodiment of this invention has been herein shown and described, it will be understood that numerous details of the construction shown may be altered or omitted without departing from the spirit of this invention as defined by the following claims.

I claim:

1. The combination of a switch, means for closing said switch, a motor actuated timing device controlling the opening of said switch, and a hammer member adapted to be set in motion by said timing device to strike a blow for suddenly starting the opening of said switch, said closing and timing devices being interconnected to coact simultaneously for manual setting thereof in their operative relations respectively.

2. In a device of the class described, the combination of a switch, mechanism for closing said switch, a motor mechanism adapted to automatically open said switch after the expiration of a predetermined interval of time after the closing thereof, and a hammer member controlled by said motor mechanism and adapted to strike a blow for suddenly starting the opening of said switch, said closing and motor mechanisms being interconnected to operate simultaneously for manual setting thereof in their operative relations respectively.

3. The combination of a switch, manually controlled and reversibly operatable means adapted when operated in one direction to close said switch, a motor adapted to be set by said manually controlled means when the latter is operated in its switch closing direction, said motor when set being arranged and adapted to automatically open said switch, an indicator actuated by said manually controlled means and adapted at any time after the switch has been closed to indicate the interval of time remaining at the expiration of which the said motor will open said switch, said switch and indicator being operatively connected to said manually con trolled means for restoration thereby when the latter is operated in its reverse direction.

4. In a device of the class described, the combination of a switch, means for closing said switch, a clockwork adapted to control the automatic opening of said switch, said clockwork being arranged to be wound through the act of closing said switch, an indicating device comprising two indicators, mechanism for simultaneously setting said indicators to like indications through the operation of said switch closing means, means whereby one of said indicators may be returned by said clockwork to its initial position independent of the other, a detent adapted to hold said other indicator in its set position during the return movement of said one indicator, means actuated by said one indicator for tripping said detent, and means normally biasing said other indicator to its initial position.

5. The combination of a machine, a motor adapted to operate said machine, a timing device adapted to control the operation of said motor and adapted to be set to cause a certain operation of said machine in a predetermined interval of time, a pair of indicators adapted through the setting of said timing device to be moved to a position for indicating the interval of time for which said device is set, one of said indicators being driven by said motor and adapted to be returned thereby to its initial position, a spring normally biasing the other of said indicators to its initial position, a detent adapted to hold said other indicator at its set position against the pull of said spring, and means actuated by said first indicator for tripping said detent.

6. In a device of the class described, the combination of a motor, a timing device adapted to control the operation of said motor during a predetermined interval of time, indicating mechanism comprising a pair of indicators one being adapted to be set through the setting of said timing device and to be returned to its normal initial position through the operation of said motor, coacting shoulders on said indicators whereby the other said indicator is set through the setting of the first said other indicator being normally biased toits initial position, a detent adapted to hold said other indicator in its set position, and means controlled by the first said indicator for retracting said detent when said first indicator returns to its initial position.

7. The combination of a switch, a rack connected to one of the switch members and adapted to be shifted for shifting said member, a spring motor mechanism having a winding key, a gear connected with said key and adapted to mesh with said rack for shifting it, means adapted to normally bias said rack out of engagement with said gear, and means connecting said winding key and rack and adapted through the rotation of said key to shift said rack into engagement with said gear.

8. The combination of a switch compris ing, a movable member, an operating member pivotally mounted and adapted to oscillate between difierent positions for respectively opening and closing said switch, a spring connected with said member and adapted to yieldingly hold the same at either limit of its movement, a hammer member adapted to strike a blow for suddenly starting the opening of said switch, means for closing said switch and simultaneously setting said hammer member, and a motor actuated timing device adapted to automatically trip said hammer member.

9. The combination of a switch comprising, a pair of coacting members, a rack adapted when shifted longitudinally to operate said switch, a spring motor havinga winding key, agear connected with said key and coacting with said rack to shift the same longitudinally, said rack and one switch member having pin and slot connection, a bar coacting with said rack and having separate connection with said one switch member, a spring normally biasing said bar into position for opening said switch, means for interlocking said bar and rack for sh tting said bar against the pressure of said spring during the closing of sa d sw tch, and a timing device adapted to trip said interlocking means to permit said spring to shift said bar for opening said switch in advance of the movement of said rack.

10. The combination of a switch comprising, a pair of coacting members, a rack adapted when shifted longitudinally to operate said switch, a spring motor having a winding key, a gear connected with said key and coacting with said rack to shift the same longitudinally, said rack and one switch member having pin and slot connection, a bar coacting with said rack and having separate connection with said one switch member, a spring normally biasing said bar into position for opening said switch, means for interlocking said bar and rack for shifting said bar against the pressure of said spring during the closing of said switch, and a timing device adapted to trip sa d interlocking means to permit said spring to shift said bar for opening said switch in advance of the movement of said rack, said bar having pin and slot engagement with said movable switch member whereby said bar will be set in motion in advance of the movement of said switch member and will iinpinge on said switch member to strike a hammer blow for starting the opening of said switch member.

11. In a device of the class described the combination of a switch having a movable member, rack and gear mechanism for manually closing said switch, a motor actuated timing device adapted to be set through the closing of said switch and adapted to automatically shift said rack for opening said switch, a hammer member connected with said rack and adapted to strike a blow on said movable switch member for opening said switch, a spring arranged to actuate said hammer member, a detent acting between said hammer mem her and rack and adapted to set said hammer member against the action of said spring through the movement of said rack, and means controlled by the movement of said rack for tripping said detent to automatically release said hammer member from said rack when said rack arrives at a certain predetermined position.

12. In a device of the class described the combination of a switch, a rack bar connected therewith for opening and closing said switch, a gear coacting with said rack bar, means for rotating said gear to close said switch, means controlled by the rotation of said gear for shifting said rack and gear out of engagement with each other whereby said gear may rotate independently of said rack, and a motor actuated timingv device connected with said gear and adapted to be wound through the closing of said switch, all being arranged to cause said rack and gear to be automatically rengaged through a predetermined angular movement of said gear.

13. In a device of the class described the combination of a switch, a rack bar connected therewith for opening and closing a said switch, a gear coacting with said rack bar, means for rotating said gear to close said switch, means controlled by the rotation of said gear for shifting said rack and gear out of engagement with each other whereby said gear may rotate independently of said rack, a motor actuated timing device connected with said gear and adapted to be wound through the closing of said switch,

iqo

all being arranged to cause said rack and gear to be automatically reengaged through a predetermined angular movement of said gear, and a hammer member adapted to be set through the movement of said rack for closing said switch and adapted to be re-,

leased through a return movement of said rack, said hammer member being adapted when released from said rack to strike a blow for starting the opening of said switch.

14. The combination of a movable switch member, a toggle spring adapted to urge the switch member toward either its open or closed positions when it has passed a certain intermediate position, a rack bar, a hammer bar controlled by said rack bar, a hammer spring connected to said hammer bar and adapted to assist said toggle spring in opening the switch, and mechanism for controlling the relative morements of said hammer bar and rack.

15. The combination of a switch, a movable switch member, a toggle spring adapted to urge said switch member toward either its open or its closed position when it has passed a certain intermediate position, a motor actuated timing device adapted to control the opening of said switch, manually operated means for closing said switch and simultaneously starting said motor timing device, and a spring put under tension by the manual closing of said switch, said spring being adapted to assist the motor in compressing said toggle spring in bringing said toggle spring to its said intermediate position.

16. The combination of a switch, a movable switch member, a toggle spring adapted to urge said switch member toward either its open or its closed position when it has passed a certain intermediate position, a spring motor actuated timing device adapted to control the opening of said switch, manually operated means for closing said switch and simultaneously winding said motor timing device, and a spring put under tension by the manual closing of said switch, said spring being adapted to assist the motor in compressing said toggle spring in bringing said toggle spring to its said intermediate position.

Signed at Platteville this 9th day of March 1912.

JOHN H. ROBERTSON.

Witnesses:

J. D. HEAD, S. W. TRABER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

